A data processing apparatus which generates a frame of image data for display by compositing several layers may be provided with one or more latency buffers. Image data for those plural layers of content can thus be temporarily stored on retrieval from memory in the latency buffer(s) before being composited to generate the final frame for display. The quantity of data which is retrieved from memory (and temporarily stored in such buffers) is generally rather large in a contemporary image processing apparatus, due in particular to the high resolution requirements for contemporary display devices. The latency buffers play an important role in ensuring that image data is already available within the compositing circuitry of the image processing apparatus in advance of being required for the compositing process, such that buffer underrun does not occur and an undesirable interruption to the provision of completed frames is avoided. The opportunity exists to improve the manner in which such latency buffers are used.